The present invention relates to flavoured foodstuffs and flavouring compositions. More in particular the present invention relates to foodstuffs having a savoury flavour and to flavouring compositions suitable for imparting such a flavour. Under a savoury flavour is here to be understood a flavour associated with meat, sausage, poultry, cheese etc. The term foodstuff as used herein includes both solid and liquid ingestible materials which may or may not have nutritional value.
Flavoured foodstuffs having a savoury flavour and flavouring compositions for imparting to and/or enhancing in a foodstuffs a savoury flavour have been known for a long time, but so far these compositions were not been quite satisfactory. Therefore the present invention aims to improve the organoleptic properties.
Many compounds have been used to impart a savoury flavour to foodstuffs and therefore most of the compositions used for a savoury flavour contain a multitude of compounds. One group of particular useful compounds for savoury flavours are certain (hydrogenated) furan thiols and derivatives thereof like thio-acetates are e.g. disclosed and/or claimed in GB-A-1 283 912 (Unilever). GB-A-1 256 462 (International Plavours and Fragrances) also discloses certain furan thiols such as 2-methylfuran-3-thiol and it derivatives such as its disulphide and other sulphides as meat flavours. Especially 2-methylfuran-3-thiol and its precursors are powerful flavouring compounds capable of imparting a pleasant roast meat flavour to foodstuffs [cf e.g. xe2x80x9cVolatile compounds in foods en beveragesxe2x80x9d methyl-3-furyldithioby H. Maarse (ED) Marcel Dekker, New York (1991)]. Its powerful roast or fried beef note is, however, not always appreciated. Therefore attempts have been made to obtain products with a powerful, somewhat milder, more rounded off meat flavour more reminiscent of the flavour of boiled beef and beef broth.
The present invention solves the problem of obtaining a powerful mild beef flavour reminiscent of beef broth, and boiled beef which is especially needed for soups, sausages, pastry etc. Also varying the relative amounts of the key components the present invention enables the flavourist to prepare flavouring compositions varying from a mild roast beef flavour to a mild beef broth flavour.
In a first embodiment the present invention therefore provides a flavoured foodstuff comprising an effective amount of at least one compound with a (hydrogenated) 2-methyl-3-furyl-thio moiety and a hydrogen atom, an xe2x80x94Sxe2x80x94CH3 group, an xe2x80x94COxe2x80x94CH, group or a 2-methyl-3-furyl-thio moiety and an effective amount of at least one compound having the structure
Uxe2x80x94CH2xe2x80x94Sxe2x80x94T
in which C, H and S have the conventional meanings of carbon, hydrogen and sulphur atoms respectively, U represents a thiol group, a lower thioacyl group, a lower thioalkylgroup, a hydroxyl group or a 2-methyl-3-furyldithio group and T represents a hydrogen atom, a lower acyl group or a 2-methyl-3-furyl-thio group or a xe2x80x94Sxe2x80x94CR2xe2x80x94U group as defined above.
Suitable compounds in the practice of the present invention having a (hydrogenated) 2-methyl-3-furyl-thio moiety and a hydrogen atom, an xe2x80x94Sxe2x80x94CH3 group, an xe2x80x94COxe2x80x94CH3 group or a 2-methyl-3-furyl-thio moiety are e.g. 2-methylfuran-3-thiol, 2-methyl-4,5-dihydrofuran-3-thiol, cis/trans 2-methyltetra-hydrofuran-3-thiol, 2-methyl-3-thiomethoxyfuran, methyl-2-methyl-3-furyldisulphide, 2-methylfuran-3-thioacetate, 2-methylfuran-3-thiopropionate and the disulphide of 2-methylfuran-3-thiol. The use of non-hydrogenated furan derivatives is preferred. Several of these compounds are available from Oxford Chemicals, Hartlepool, U.K. It is observed that 2-methylfuran-3-thiol like many other thiols is liable to oxidise partially under the influence of oxygen in the atmosphere to its disulphide and consequently quite often commercially available 2-methylfuran-3-thiol preparations contain certain amounts of its disulphide. Thioesters like 2-methyl-3-furan-3-thioacetate and e.g. 2-methyl-3-furan-3-thiopropionate may hydrolyze partially to form 2-methyl-3-furan-3-thiol under certain food processing conditions. This may apply e.g. under the conventional sterilising conditions after canning.
Suitable compounds for the practice of the present invention having a (hydrogenated) 2-methyl-3-furyl-thio moiety and a hydrogen atom, an xe2x80x94Sxe2x80x94CH3 group, an xe2x80x94COxe2x80x94CH3 group or a 2-methyl-3-furyl-thio moiety and an effective amount of at least one compound having the structure
Uxe2x80x94CH2xe2x80x94Sxe2x80x94T
in which C, H and S have the conventional meanings of carbon, hydrogen and sulphur atoms respectively, U represents a thiol group, a lower thioacyl group, a lower thioalkylgroup, a hydroxyl group or a 2-methyl-3-furyldithio group and T represents a hydrogen atom, a lower acyl group or a 2-methyl-3-furyl-thio group or a xe2x80x94Sxe2x80x94CH2xe2x80x94U group as defined above are methanedithiol, methanedithiol diacetate, methylthiomethanol, methylthiomethanethiol, methylthiomethanethiol acetate, methylthiomethanethiol propionate, methylthiomethanethiol 2-methylpropionate, methylthiomethanethiol 2-methylbutanoate, methylthiomethanethiol 2-methylbutanoate, 3-methylthiomethanethiol pentanoate, methylthiomethanethiol 4-methylpentanoate and methylthiomethanethiolhexanoate. Some of these compounds are to be regarded as precursors of the corresponding free thiols, whereas others have organoleptic properties resembling methanedithiol or methylthiomethanol etc. with slightly different flavour notes. Here also the possibility arises that free thiols are partially converted to corresponding disulphides under oxidising conditions and also thioesters may hydrolyse to form free thiols under certain food processing conditions.
The present invention not only covers foodstuffs flavoured by incorporating the above identified compounds per se, but also foodstuffs incorporating precursors of the above identified compounds.
2-Methyl-3-furanthiol and some of its derivatives discussed above can be obtained or synthesized as such, but it may also be convenient to prepare a meat/beef flavour composition containing one or more of these compounds (a reaction flavour composition) which comprises at least one of these compounds in a suitable quantity and incorporate in such a composition a suitable amount of a compound having the structure Uxe2x80x94CH2xe2x80x94Sxe2x80x94T. Suitable reaction flavour compositions can be prepared by reacting a hexose or pentose with a source of hydrogen sulphide such as cysteine in water as a solvent. Instead of a hexose or pentose a suitable degradation product of a sugar can be used such as e.g. 4-hydroxy-5-methyl-2,3-hydrofuran-3-one and ascorbic acid may also be used. It is also quite possible to prepare suitable reaction flavours containing 2-methyl-3-furanthiol by thermal degradation of thiamine. Several possibilities and reaction mechanisms of reaction flavours are discussed by Hoffmann and Schieberle in J. Agric. Food Chemistry, 46, 235-241 (1998) which is hereby incorporated by reference.
The flavouring compositions according to the present invention are especially incorporated in foodstuffs such as sausage, meat, reformed communicated meat, meat replacers such as texturized vegetable protein, and pastry products in an effective amount, i.e. in an amount sufficient to impart or reinforce the desired flavour. As a general guide flavouring amounts of 0.01 to 1000, preferably 0.5 to 100 ppb (parts per billion=1:109) are incorporated in foodstuffs which proportions are expressed as one a weight basis calculated on the foodstuff. The flavouring amounts actually incorporated depend on the individual palate and on the nature of the foodstuff. In flavouring compositions the amounts present may easily be a factor 10 to 10,000 higher than in the actual flavoured foodstuff.
Preferably the present invention provides a flavoured foodstuff as defined above, in which lower thioacyl- and lower acyl group means that these groups comprise from 2 to 6, preferably 2 or 3 carbon atoms.
Preferably the present invention provides a flavoured foodstuff as defined above,in which U represents a lower thioacyl group and T represents a lower acyl group.
More preferably the present invention provides a flavoured foodstuff as defined above, in which lower thioacyl group means thioacetoxy and lower acyl group independently means acetyl.
In another embodiment the present invention provides a process for imparting a savoury flavour to a foodstuff comprising incorporating in said foodstuff an. effective amount of at least one compound with a 2-methyl-3-furyl-thio moiety and a hydrogen atom, an xe2x80x94Sxe2x80x94CH3 group, an xe2x80x94COxe2x80x94CH3 group or a (hydrogenated) 2-methyl-3-furyl moiety and an effective amount of at least one compound having the structure
Uxe2x80x94CH2xe2x80x94Sxe2x80x94T
in which C, H and S have the conventional meanings of ah carbon, hydrogen and sulphur atoms respectively, U represents a thiol group, a lower thioacyl group, a lower thioalkylgroup, a hydroxyl group or a 2-methyl-3-furyldithio group and T represents a hydrogen atom, a lower acyl group or a 2-methyl-3-furyl-thio moiety or a xe2x80x94Sxe2x80x94CH2xe2x80x94U group as defined above.
Preferably the above process according to the present invention employs compounds as defined above, in which lower thioacyl-, lower alkyl- and lower acyl group means that these groups comprise from 2 to 6, preferably 2 or 3 carbon atoms.
More preferably the above process according to the present invention employs at least one compound as defined above, in which U represents a lower thioacyl group or a lower acyloxy group and T represents a lover acyl group.
In an other embodiment the present invention provides a flavouring composition for foodstuffs comprising at least one compound comprising a (hydrogenated) 2-methyl-3-furyl-thio moiety and a hydrogen atom, an xe2x80x94Sxe2x80x94CH3 group, an xe2x80x94COxe2x80x94CH3 group or a (hydrogenated) 2-methyl-3-furyl-thio moiety and at least one compound having the structure
xe2x80x83Uxe2x80x94CH2xe2x80x94Sxe2x80x94T
in which C, H and S have the conventional meanings of carbon, hydrogen and sulphur atoms respectively, U represents a thiol group, a lower thioacyl group, a hydroxyl group or a 2-methyl-3-furyldithiogroup and T represents a hydrogen atom, a lower alkyl group or a lower acyl group. Such a flavouring composition can be used for enhancing an existing weak savoury flavour e.g. to compensate for flavour notes lost by processing foodstuffs, but they can equally be used for flavouring a bland or tasteless foodstuff. Moreover it is also possible to change the flavour characteristics of a foodstuff completely. Flavouring compositions are frequently available in the form of active material in a suspension or a solution or upon an organoleptically inactive material.
Preferably the flavouring composition for foodstuffs according to the present invention comprises at least one or more compounds as defined above, in which lower thioacyl-, lower alkyl- and lower acyl group means that these groups comprise from 2 to 6, preferably 2 or 3 carbon atoms.
The flavouring compositions for foodstuffs may be in liquid or semi-liquid form such as solutions, emulsions or pastes, or in dry form such as a powder. Drying can be accomplished for example by spray-drying or by freeze-drying, optionally on a carrier such as maltodextrin.
The present invention is not restricted to at least one compound with a (hydrogenated) 2-methyl-3-furanthiol (derivative) together with at least one compound with a methylenedithiol (derivative) as defined above. As is common in flavour creation other compounds known to contribute to a savoury flavour can be incorporated as well. Such known compounds are e.g. amino acids, nucleotides, monosodiumglutamate, lower alcohols, lower carboxylic acids, pyrrolidone carboxylic acid, lower peptides, sweeteners, lactones, lower disulphides, lower thiols, guanidines etc., salts like NaCl, amines, lower aldehydes, lower ketones, tricholomic acid, biotenic acid, aromatic and/or heterocyclic compounds like acetyl thiazole, 2-hydroxyethyl-4-methylthiazol, 4-hydroxy-2,5-dimethyl-2,3-hydrofuran-3-one, colouring materials, thickening agents. The proportions of these optionally added substances used are dependent on the kind of flavour desired and also on the nature of the foodstuffs in which they are incorporated and also on any herbs or spices added.
According to another embodiment the present invention provides the use of both an effective amount of at least one compound with a (hydrogenated) 2-methyl-3-furyl-thio moiety and a hydrogen atom, an xe2x80x94Sxe2x80x94CH3 group, an xe2x80x94COxe2x80x94CH3 group or a 2-methyl-3-furyl-thio group and an effective amount of at least one compound having the structure
Uxe2x80x94CH2xe2x80x94Sxe2x80x94T
in which C, H and S have the conventional meanings of carbon, hydrogen and sulphur atoms respectively, U represents a thiol group, a lower thioacyl group, a lower thioalkylgroup, a hydroxyl group or a 2-methyl-3-furyldithio group and T represents a hydrogen atom, a lower acyl group or a 2-methyl-3-furyl-thio group or a xe2x80x94Sxe2x80x94CH2xe2x80x94U group as defined above.
According to another embodiment of the present invention provides a process for preparing a pure compound with at least one free thiol group as defined in claim 1 by hydrolysing the corresponding thioacyl compound in the presence of an enzyme or a cation exchange resin.
More preferably the process defined above comprises the use of a lipase. More in particular lipases like lipase 435 ex NOVO, Denmark can be used with good results.